Question

The sum of all even natural number between 1-31 ?

Answer 1

All even natural numbers include 2,4....30
If you have studied arithmetic progression you will recognise this simple formula.
the first term is 2,the difference between the consecutive terms is also 2.
Sum=(first term + last term)(no. of terms )/2
=(2+30)(15)/2
=16×15
=240

You can find the no. of terms by observing the series
2×1=2
2×2=4
..
...
....
2×15=30
Comment if there's any doubt.

Answer 2

Heya ☺

________________________________________________________________

First of all the even numbers between 1 - 31 -:

➡2,4,6,8,10,12,14,16,18,20,22,24,26,28,30

Now their sum = 2+4+6+8+10+12+14+16+18+20+22+24+26+28+30 = 240

__________________________________________________________

#hope it helps☺